Jackson said he was thinking of Hall of Famer Barry Sanders, who retired when he was less than 1,500 yards from becoming the NFL's all-time leading rusher. He said he didn't want to extend his career too long.

Jackson, 29, is expected to decline his $7 million player option for the 2013 season, which would make him a free agent.

Jackson had 257 carries for 1,042 yards and four touchdowns this season and has rushed for 1,000 yards or more in each of the past eight seasons. In his nine-year NFL career, all with the Rams, Jackson has rushed for 10,135 yards and 56 touchdowns.